Prior art pedal assemblies generally comprise a pedal housing attached to a vehicle body and a pedal arm pivotally supported by the pedal housing. A series of links and levers, or cables, mechanically connect the pedal assembly to an engine throttle. Therefore, movement of the pedal arm mechanically controls a position of the engine throttle. In addition, a kickdown device is mechanically connected to the pedal assembly. The kickdown device is used to initiate a kickdown, i.e., a downshift to a next lower gear in an automatic transmission. Typically, such downshifts occur when a user desires fast acceleration. For instance, when the pedal arm is pivoted from an idle position to a predetermined operable position, the kickdown device is mechanically engaged to downshift the automatic transmission. As a result, an added force is required to further pivot the pedal arm. This added force provides a sensation to the user that is commonly referred to as a kickdown feel, i.e., the user can “feel” when the kickdown device is engaged, and hence, when the automatic transmission downshifts to the next lower gear.
Consequently, a large amount of packaging space must be provided within the vehicle to accommodate the mechanical connections to the kickdown device and the engine throttle. However, the space available for the mechanical connections is limited. Hence, recent improvements in the prior art use electrical connections in place of the mechanical connections. Instead of using the mechanical connections to mechanically transmit a position of the pedal arm to the engine throttle or kickdown device, an electrical generator is used to electrically transmit the position of the pedal arm and subsequently control the engine throttle and the kickdown. Replacing the mechanical connections with electrical connections reduces the necessary packaging space for the pedal assembly.
In prior art electronic pedal assemblies, the electrical generator generates a control signal that varies in magnitude with respect to the position of the pedal arm relative to the pedal housing. The control signal is sent to a controller that is responsive to the electrical generator. A processor in the controller uses the control signal to generate other control signals to control the position of the engine throttle and to control the downshift. In general, the downshift occurs when the control signal has a predetermined magnitude and the controller, in response, instructs the automatic transmission to downshift to the next lower gear. In other words, the controller is programmed to control the automatic transmission to downshift to the next lower gear when the control signal has the predetermined magnitude.
Unfortunately, without the mechanical connections, electronic pedal assemblies do not provide the customary feel and performance of a mechanically connected pedal assembly. In other words, the pedal assembly does not provide the kickdown feel to the user when the downshift occurs, i.e., the user cannot “feel” when the downshift occurs. To solve this problem, manufacturers incorporate a kickdown mechanism in the electronic pedal assembly to provide the kickdown feel to the user. The kickdown mechanism is markedly different than the kickdown device described above. The kickdown device is mechanically connected to the pedal assembly via a link or cable and mechanically initiates the downshift in the automatic transmission. Conversely, the kickdown mechanism does not initiate the downshift. Unlike the kickdown device, the kickdown mechanism is a stand-alone mechanism simply used to provide the kickdown feel to the user. Typically, the kickdown mechanism provides the added force associated with the kickdown feel via a kickdown member that engages a portion of the pedal arm.
An example of a kickdown device mechanically connected to the pedal assembly to initiate a downshift in an automatic transmission is shown in U.S. Pat. No. 5,697,253 to Papenhagen et al.
An example of a kickdown mechanism used in an electronic pedal assembly to provide a kickdown feel is shown in U.S. Pat. No. 6,209,418 to Kalsi et al. The kickdown mechanism in the '418 patent utilizes a kickdown member that engages a portion of a pedal arm.
Even with the kickdown member to simulate the kickdown feel, prior art electronic pedal assemblies cannot control a position of the kickdown member to ensure that the pedal arm will engage the kickdown member when the pedal arm is at a predetermined operable position. This can present problems when the predetermined operable position coincides with downshifting of the automatic transmission. Without the ability to control a position of the kickdown member, there is a significant likelihood that the kickdown feel provided by the kickdown member will not occur when the downshift occurs. A typical prior art electronic pedal assembly includes many tolerances between the kickdown member and the pedal arm and between the pedal arm and the electrical generator. Thus, a fixed kickdown member is unlikely to be engaged by the pedal arm when the pedal arm is at the predetermined operable position. Therefore, there exists a need in the art for an electronic pedal assembly capable of adjusting the kickdown member and ensuring that the pedal arm is at the predetermined operable position when the pedal arm engages the kickdown member.